Pyridyl amines have been used to prepare Group 4 complexes which are useful transition metal components in the polymerization of alkenes, see for example US 2002/0142912, U.S. Pat. Nos. 6,900,321, and 6,103,657, where the ligands have been used in complexes in which the ligands are coordinated in a bidentate fashion to the transition metal atom.
WO 2005/095469 shows catalyst compounds that use tridentate ligands through two nitrogen atoms (one amido and one pyridyl) and one oxygen atom.
US 2004/0220050A1 and WO 2007/067965 disclose complexes in which the ligand is coordinated in a tridentate fashion through two nitrogen (one amido and one pyridyl) and one carbon (aryl anion) donors.
A key step in the activation of these complexes is the insertion of an alkene into the metal-aryl bond of the catalyst precursor (Froese, R. D. J. et al., J. Am. Chem. Soc. 2007, 129, 7831-7840) to form an active catalyst that has both a five-membered and a seven-membered chelate ring.
WO 2010/037059 discloses pyridine containing amines for use in pharmaceutical applications.
US 2012/0071616 A1 discloses pyridyldiamide catalyst complexes incorporating an NNN ligand having a neutral pyridine donor and two anionic amide donors that are substituted with a phenyl group and a 2,6-diisopropylphenyl group, but not hydrocarbyl groups having 1 to 20 carbon atoms and having an H/C ratio of 1.66 or higher where the carbon atom bonded to the nitrogen is not a tertiary carbon atom.
Additional references of interest include: Vaughan, A; Davis, D. S.; Hagadorn, J. R. in Comprehensive Polymer Science, Vol. 3, Chapter 20, “Industrial catalysts for alkene polymerization;” Gibson, V. C.; Spitzmesser, S. K. Chem. Rev. 2003, 103, 283; Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem. Int. Ed. 1999, 38, 428; U.S. Pat. Nos. 7,973,116; 7,446,216; 7,812,104; 7,276,567; 7,667,064; 7,868,197; 7,557,171; 7,538,168; US 2011/0224391; US 2011/0301310; U.S. Ser. No. 61/815065 filed Apr. 23, 2013; US 2010/0227990 (note catalyst structures bind to the metal center with a NNC donor set); WO/0238628 A2 (note ligands bind to the metal center with a NNC donor set); and Guerin, F.; McConville, D. H.; Vittal, J. J. Organometallics 1996, 15, 5586 (note NNN-donor set does not contain a 7-membered chelate ring or dihydroindenyl- and/or tetrahydronaphthalenyl-groups).
There still is need for adding synthetic routes to widen the range of catalysts complexes that may be prepared and broaden their performance in alkene polymerization. The performance may be varied with respect to the amount of polymer produced per amount of catalyst (generally referred to as the “activity”) under the prevailing polymerization conditions; the molecular weight and molecular weight distribution achieved at a given temperature; and the placement of higher alpha-olefins in terms of the degree of stereoregular placement.
Further, improved catalyst productivity is desired because it reduces in use catalyst cost. Additionally, single-site catalysts that produce high molecular weight, highly crystalline polypropylene are rare, yet desired for the production of polypropylene containing products of high stiffness.
This need is addressed by the new pyridyldiamide (PDA) catalysts disclosed herein. In propylene polymerization studies, these catalysts were found to have both improved activity and to produce higher melting point polymer.